#include <fstream>
#include <algorithm>
#include <vector>
#define pb push_back
using namespace std;
ifstream f("biconex.in");
ofstream g("biconex.out");

typedef pair< int, int > edge;
int N, M, order, x, y, low[100002], found[100002], dad[100002];
vector < int > G[100002], Part;
vector < edge > CritEdge, st;
vector < vector<int> > BCC;

template <class T>
inline void ElimDuplicate(vector < T > &V)
{
    sort(V.begin(), V.end());
    V.erase( unique(V.begin(), V.end()), V.end());
}

void getbcc(edge M)
{
    vector <int> newbcc; edge E;
    do
    {
        E=st.back(); st.pop_back();
        newbcc.pb(E.first); newbcc.pb(E.second);
    } while (E!=M);
    ElimDuplicate(newbcc); BCC.pb(newbcc);
}

void dfs(int nod)
{
    low[nod]=found[nod]=++order;
    int sons=0;
    vector <int>::iterator it=G[nod].begin();
    for (; it!=G[nod].end(); ++it)
        if (!dad[*it])
        {
            dad[*it]=nod; st.pb(edge(nod, *it));
            ++sons; dfs(*it);
            low[nod]=min(low[nod], low[*it]);

            if (dad[nod]!=nod && low[*it]>=found[nod])
                Part.pb(nod);

            if (low[*it]>=found[nod])
                getbcc(edge(nod, *it));

            if (low[*it]>found[nod])
                    CritEdge.pb(edge(nod, *it));
        }
        else if (*it!=dad[nod])
            low[nod]=min(low[nod], found[*it]);
    if (sons>1 && dad[nod]==nod) Part.pb(nod);
}

void tarjan()
{
    for (int i=1; i<=N; ++i)
        if (!dad[i])
            dad[i]=i, dfs(i);
    ElimDuplicate(CritEdge); ElimDuplicate(BCC);
}

void printBCC()
{
    g<<BCC.size()<<'\n';
    for (int i=0; i<(int)BCC.size(); ++i && g<<'\n')
        for (int j=0; j<(int)BCC[i].size(); ++j)
            g<<BCC[i][j]<<' ';
}

void printPart()
{
    g<<Part.size()<<'\n';
    for (int i=0; i<(int)Part.size(); ++i)
        g<<Part[i]<<' '; g<<'\n';
}

void printCritEdge()
{
    g<<CritEdge.size()<<'\n';
    for (int i=0; i<(int)CritEdge.size(); ++i)
        g<<CritEdge[i].first<<' '<<CritEdge[i].second; g<<'\n';
}

int main()
{
    f>>N>>M;
    for (int i=1; i<=M; ++i)
        f>>x>>y, G[x].pb(y), G[y].pb(x);
    tarjan(); printBCC();
    return 0;
}